This invention relates to the water-testing of an article by running a flow of water through the article, and more particularly to the water-testing of a hollow turbine airfoil component having multiple flow channels therethrough.
Some types of turbine airfoil components are made hollow with air flow channels therethrough, extending from the base of the turbine airfoil component to openings at various locations on the surface of the turbine airfoil component. During service, a flow of cooling air is introduced into the air flow channels at the base. The cooling air flows through the interior of the turbine airfoil component to emerge from the openings. Heat is removed from the turbine airfoil component by the air flow. Additionally, the air flow from the openings provides a film of cool air over the surface of the turbine airfoil component to protect it from hot combustion gases.
The hollow interior of the turbine airfoil component is typically divided into multiple regions, both to provide internal structural stiffening and also to define separate air flow channels. The separate air flow channels may lead, for example, to respective sets of exterior surface openings along the leading edge of the turbine airfoil component, along the trailing edge of the turbine airfoil component, and along the concave or pressure-side of the turbine airfoil component which is directly contacted by the flow of hot combustion gases.
The turbine airfoil component is typically manufactured by casting it with the internal air flow channels in place, and then drilling the openings from the exterior surface to the air flow channels. The turbine airfoil component is thereafter coated on portions of its exterior surface, and optionally on its interior surface of the air flow channels. The coatings form protective layers and possibly insulating layers on the surfaces, to extend the life of the turbine airfoil component.
At various stages of the manufacturing operation, the turbine airfoil component is water tested to ensure that the openings from the gas-flow channels to the exterior surface are clear and free from blockage. Blocked or nearly blocked openings may result, for example, from a defect when the opening is formed or from a partial or complete closure of the opening during the coating process. In water testing, the base of the turbine airfoil component is held in a fixture to a water source, and water flows along generally the same flow path as air flows in service, from the base, through the air flow channels, and out the openings. The water flow out of the openings is observed to determine whether the flow from each and every opening is sufficient and indicative of an unobstructed opening.
In the work leading to this invention, the inventors have observed that in some cases it is very difficult to visualize the flow from each of the openings served by the various flow air channels. Consequently, it is difficult to be certain that the openings are properly sized and free of obstructions. Accordingly, there is a need for a better technique and apparatus for testing water flow through such hollow articles. The present invention fulfills this need, and further provides related advantages.
The present invention provides an apparatus and method for water-flow testing of hollow articles such as turbine airfoil components with multiple internal water-flow channels. The present approach allows the water flow through the various sets of openings to be more readily visualized. Additionally, the apparatus is mechanically easier to use than available conventional devices.
A water-flow testing apparatus for testing an article having at least two water flow passage article inlets comprises an apparatus body having a water inlet and an attachment head integral with the apparatus body. The attachment head includes a holder that receives the article therein in sealing contact with an article seal, and at least two ports, each port being in registry with at least one of the water flow passage article inlets. A water flow controller within the apparatus body has a controller inlet in water-flow communication with the water inlet, at least two controller outlets, with each controller outlet being in water-flow communication with one of the ports of the attachment head, and a flow-control valve disposed in a water flow path between the controller inlet and the controller outlets. The flow-control valve is controllable to controllably connect a single one of the controller outlets at a time to the controller inlet.
In one preferred embodiment, the holder comprises a jaw mechanism that engages the article on two opposite sides of the article when open and draws the article toward the article seal as the jaw moves toward a closed position. The holder may further comprise a spring that biases the jaw toward the closed position. The article seal comprises a piece of rubber with the at least two seal inlets therethrough. The flow-control valve comprises a valve bore in water-flow communication with each of the controller outlets, a valve core slidably received within the valve bore, the valve having a channel therethrough that may be slidably aligned with each controller outlet, and a sliding core seal at each end of the valve bore to slidingly seal the valve core to the valve bore.
Preferably, a water-flow testing apparatus is provided for testing a turbine airfoil component having at least two water flow passage turbine airfoil component inlets in a base thereof and an external dovetail region on an external surface of the base. The water-flow testing apparatus comprises an apparatus body having a water inlet, and an attachment head integral with the apparatus body. The attachment head includes an article seal, wherein the article seal comprises a piece of rubber with at least two seal inlets therethrough, each seal inlet being in registry with at least one of the at least two water flow passage turbine airfoil component inlets, and a holder that receives the turbine airfoil component therein in sealing contact with the article seal. The holder comprises a jaw mechanism having camming surfaces that engage the turbine airfoil component on the dovetail region when open and draws the base of the turbine airfoil component toward the article seal as the jaw mechanism moves toward a closed position. A spring biases the jaw mechanism toward the closed position. A water flow controller within the apparatus body has a controller inlet in water-flow communication with the water inlet, at least two controller outlets, with each controller outlet being in water-flow communication with one of the seal inlets of the attachment head, and a flow-control valve disposed in a water flow path between the controller inlet and the controller outlets. The flow-control valve is controllable to controllably connect a single one of the controller outlets at a time to the controller inlet. The flow-control valve comprises a valve bore in water-flow communication with each of the controller outlets, a valve core slidably received within the valve bore, with the valve core having a channel therethrough that may be slidable aligned with each controller outlet, and a sliding core seal at each end of the valve bore to slidingly seal the valve core to the valve bore.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The scope of the invention is not, however, limited to this preferred embodiment.